Lapping arm



H. S. lN-DGE LAPPING ARM March 28, 1950 3 snets-Sheet 1 Filed June 16, 1949 I 7a2/sentar HE/eE/zr NDGE By March 28, 1950 H. s. INDG 2,502,381

LAPPING ARM Filed June 16, 1949 sheets-sheet a [Rz/enter March 28, 1950 H. s. INDGE 2,502,381

LAPPING ARM Filed June 16, 1949 3 Sheets-Sheet 3 H HHIHIH l illll 3l Flg 7 54 u] aafla (p4 q 7o u be r V \1 @7 mi 73 y e 21a Patented Mar. 28, 1950 UNITED STATES Meur OFFICE LAPPING ARM Application June 16, 1949; Serial No. 99,375

6 Claims. l

The invention relates to lapping machines and more particularly to' an improved lapping apparatus for lapping cylindrical surfaces such as crank pins and the like.

@ne object of the invention is to provide a simple and thoroughly practical crankshaft lappingv machine. Another object 'of the invention is to provide an improved lapping arm. Another object is to provide a lapping arm having a plurality of self-aligning lapping elements. A further object of the invention is to provide a lapping arm having a plurality of lapping elements each of which may be precisely adjusted by means oi' a nut and sorew mechanism. A iurther object of the invention is to'provid-e a compound screw adjustment for the lapping elements of, a crankshaft lapping machine. Another object of the invention is to provide a lapping arm having. a plurality of lapping elements with precisi-on screw adjusting mechanisms whereby the lapping element or elements may be adjusted to com-pensate icrtaper' on' a Work piece.

yA further object of the invention is to provide an improved lapping arm construction which may be applied to a lapping machine such as, ior example, that shown in my prior U. Patent No. 2,166,009,date'd July 11, 12939. Other objects will bein part obvious or in part pointed out hereinafter.

Thel invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts, `as will be exemplified in the structure to be hereinafter described, and the scope of the application of which will be indicated in the followingy claims.

In the accompanying drawings. in which is shown one of various possible embodiments of the mechanical features of this invention,

Fig. 1 is a side elevation of the improved lapping arm together with the supporting mechanism therefor;

Fig. 2 is a fragmentary side elevation, on an enlarged scale, having parts broken away and shown in section to illustrate` the mechanism for supporting and adjusting the lapping elements, with the lapping elements in engagement with a work piece;

f Fig. 3` is a similar fragmentary side elevation, on an enlarged scale, `with the lapping elements and associated parts in an inoperative position;

Fig. 4f is a cross sectional view, on an enlarged scale, taken approximately on the line 4 4 of Fig. 3, showing the adjusting mechanism` and self-aligning. mounting for one of the lapping elements;`

Fig. 6 is a cross .sectional View, on an enlarged scale, taken approximately on the line I-G of Fig.. 3; showing the adjusting mechanism and the self-aligning mounting for one of the lapping elements. *Y

A crankshaft lapping machine of the type shown in. my prior U. S. Patent No. 2,166,009 is provided with apair of parallel lapping arm supporting rods or slides ill and II which serve as supports for a plurality of lapping arm supporting members I2', only one of which has been illustrated in the present drawings. The supporting member I2 is provided with a lower half I3 which is clamped to the member I2 by means of clamping screws I4 and I5. The supporting member I2 and lowerr half I3 are each formed withsurfaces which mate with the supporting rods or slides I and Il. It will be readily apparent from the foregoing disclosure that by loosening the` clamping screws I4 and l5 (Fig. 1), the supporting member I2 may be adjusted longitudinallyreiativeto the supporting rods or slides lill and Il to align the lapping mechanism with the work piece to be lapped. After the supporting member l2 has been initially adjusted, it may be clamped in adjusted position by tightening the clam-ping screws I4 and I5.

The lapping arm supporting member I2 serves as a support for apivotally mounted arm I6. A pivotal connection IT is provided between the supporting n'iember` l2' and the pivotally mounted arm' I6. A lapping arm I8 is pivotally connected by a. pivotal connection I9 to the upper end of the arm It willv be readily apparent from the foregoing disclosure that` the arm I8 is free to swing on the pivotal connection I9 and is free to move longitudinally by swinging the arm I6 on the pivotal support i1.

The. lapping arm IS comprises a pair of parallel side plates which are spaced apart by a plurality of spacing blocks 20, 2l, 22, 23 at one end and by a` bracket 2li'.r at the other end which is conn'ected to the pivotal connection I9`. The lappingl lapping elements 3l and 32 may be metallic elements such as for example cast iron in which case a lapping compound is fed to the work and lapping elements in a manner to be hereinafter described. If desired however the lapping elements 3l and 32 may be made of bonded abrasive material such as aluminum oxide, silicon carbide or diamond bonded by any of the well known standard bonding mediums.

A precision adjusting mechanism is provided for adjusting the lapping elements 3| and 32 relative to the work piece being lapped. These mechanisms are preferably compound screw mechanisms whereby a relatively coarse right and left hand thread may be utilized to obtain a relatively ne feeding movement of the lapping elements. As illustrated in the drawings a pair of adjusting screws 33 and 34 may be formed with a 32;-16 R. H. thread which mates with correspondingly threaded apertures in the lever 25. i

The screws 33 and 34 are provided with threaded apertures which may be provided with for example a 11G-20 L. H. thread. A screw 31 is provided having a L. H. thread to mate with the L. H.

threaded aperture 33. It will be readily appar- -f ent from the foregoing disclosure that by rotation of the screws 33 and 34 relative to the lever 25 and to the screw 21, a relatively ne feeding adjustment of the lap holders 29 and 39 may be obtained.

It is desirable that the lapping elements 3l and 32 be provided with a self-aligning mounting so that the lapping elements may readily align themselves with the peripheral surface of the Work to be lap-ped. The screw 31 is provided with a spherically-shaped end 38 which mates with a partial internal spherical surface 39 formed adjacent to one end of an elongated aperture 40 (Fig. 4) It will be readily apparent that the lap holder 29 may rock on the spherical end 38 of the screw 31 to align the operative surface of the lapping element 3l with the work piece to be lapped.

Itis desirable to provide a suitable mechanism for detachably holding the lap holder 29 on the spherical end 38 of the screw 31. This mechanism may comprise a diametrically arranged hole 4l formed in the spherical end 33. The lap holder 29 is provided with a pair of opposed aligned spring pressed detents 42 and 43 which f are arranged to engage with the opposite ends of the hole 4l. It will be readily apparent that due to the spring pressed detents 42 and 43, the lap holder 29 will be free to rock in a plane normal to the axis of the work piece being lapped to align the operative surface of the lapping element 3| with the surface being lapped. The detents 42 and 43 also serve to detachably hold a lap holder 29 and the lapping element 3l' in supporting engagement with the lever 25.

The adjusting screw 34 is similarly provided with a R. H. thread 44 which mates with a correspondingly threaded aperture in the lever 25. The screw 34 is provided with a L. H. threaded aperture 45 which engages or meshes with a L. H. screw 46. The screw 46 is provided with a spherically shaped end 41 which mates with a partial spherical surface 48 formed in the lap holder 30. The spherical end 41 is provided with a diametrically arranged hole 49. The lap holder 32 is provided with a pair of spaced aligned spring pressed detents 5D and 5l by means of which the lap holder 39 and the arcuate-shaped lapping element 32 may be detachably supported on the spherical end 41 of the screw 46 and due to the justed position.

spherical support thereof, the lapping element 32 will align itself with the surface of the work piece to be lapped when moved to an operative position.

The lapping elements 3| and 32 are provided with arcuate-shaped lapping surfaces 52 and 53 which are shaped to correspond with the surface on the work piece to be lapped. In order to facilitate a precise adjustment of the lapping elements 3l and 32, the heads of the adjusting screws 33 and 34 are serrated. A pair of spring latches 55 and 55 are fixedly mounted on the lever 25 and are arranged to engage the serrations in the heads of the screws 33 and 34 respectively to hold the screws 33 and 34 in ad- The springs 55 and 56 have sufficient spring pressure to maintain the screws in adjusted position but are such that a manual adjustment of the screws is readily obtained.

In the lapping of relatively large diameter cylindrical work pieces, it is desirable to provide a suitable adjustment for the lapping element so that compensation may be made to correct a tapered condition on the surface of the work piece being lapped. This is preferably accomplished by providing a second pair of screws which are arranged parallel to the adjusting screws 33 and 34, only one of which has been illustrated in Fig. 4 of the drawings. As illustrated in Fig. 4, an adjusting screw 33a is provided having a R. H. thread 35a which mates with a R. H. threaded aperture in the lever 25 which is parallel to the threaded aperture supporting the screw 35. The screw 35a is provided with an internally L. H. threaded aperture 33a which meshes with or engages a L. H. screw 31a. The L. H. screw 31a is provided at its right'I hand end (Fig. 4) with a spherical end 38a which mates with a partial internal spherical surface 39a formed inthe elongated aperture 43. The spherical end 38a is similarly provided with a diametrically arranged hole 4|a which serves with a pair of spring pressed detents (not shown) to provide a self-aligning movement of the lap holder 29 and also to facilitate removal of the lap holder 29 when desired. It will be readily apparent from the foregoing disclosure that by manipulation of the screws 33 and 33a, the lapping element 3l may be adjusted relative to the axis of the work piece being lapped so as to compensate or correct for any tapered condition on the peripheral surface thereof. A similar parallel screw adjustment is provided for the lap holder 3U. This construction is identical with that just described and consequently has not been illustrated and described in detail. An adjusting screw mechanism arranged parallel to the adjusting screw 34 is provided to facilitate adjustment of the lapping element 32 to compensate for taper on the work piece.

The adjusting screws 33 and 33a and also the adjusting screws 34 and the adjusting screw parallel thereto are preferably arranged so that when the lapping elements 3l and 32 are in operative engagement with the peripheral surface of the work piece 54 to be lapped, the adjustment thereof will in each case be in a radial plane passing through the axis of the work piece 54. As previously described both of the lapping elements 3i and 32 are arranged with selfaligning mountings so that they may rock about axes which are substantially parallel with the axis of the work being lapped. The lapping elements 3l and 32 may be adjusted independently to correct for any tapered condition on the work piece be.i lapped se; that; a. true eyl'lndrieatV surface; wilt be produced on. the periphery of; the.- work'. Diete MS..

lapl holder 6m. whichi Supports; an. arcuate;-

sjhapect lapping` element. is adjnstably mounted` v dmatesnvitn orfmesheswithra threadedcaperture extending1 through the:` leven 26. The: screw. 1.01 iszprovided. with a; serra-ted: head.` orknob H... The. level'l supports a.. spring latel'r 12S which is ar'- ranged to. engage ther serrations formed. on the. head 12| to?. maintain; the.v screw 10i inf. adjusted. positionl The dovetail'ed slid'eway 6.2..l and:` theJ dovetaled slide 63' are'` looselyfitted.` soi that. thel lapl holder 60` ther lapping element. 6 Il aref free to: move in. a` tangential. directionrelative tothe peripheral'. surface of the work piece 54 being lappedl to. align! the; arcuate surface '[3l of.' the lapping: elementz'l withthe surface-tube lapped; Inorder to. limit: the aligning-movement: of the lap. holder 60.',I a studf95 issupported bythe lever 2.6. (Fig. 2)v and' is heldiin. adjustede positionthereon by. means of: a. clamping;- screvv 9.6. The Stud'. 95v projects. into.` cl'earaneeholes 1 921: and 98'. formed in. the supporting. blocks; 64g and: the` lap holder B82 respec. tively.: I-t= willi beA readilyxapparentfromi the foregoing'disclosureithat a tangential. aligning move-4 ment ofi the lafp-.hol'der` imay be had: in either direction.v asalimitedzby. the clearance betweenthe stud: 125s andthe clearanceA holes Tf1.- and 1.8. pre viously. described. It. willi: be= readily apparent 4from the: foregoing disclosure that' the= lapping elements 31. andi 32M are freeto rock'v when movedintox oper-ativeh engagementl with thel periphery offthev-workf piece 54 toibo-lappedl to alignvtnemselves with the peripheral surface thereofandthe lapping elementGl'liislfree to slide in a tangential direction relative to the peripheral surfaceof the work piece 54f't'o align the lapping element 6I with the surface thereof.

'A suitable manually operable mechanism is provided for moving the levers 25 and 2B together with the lapping elements 3| and 32 and 6| respectively to and from an operative position. This mechanism may comprise a pair of toggle levers and T6 having their opposite ends pivotally connected by studs 'l1 and 18 respectively with the levers and 26 respectively.` The inner ends of the toggle levers 'I5 and 16 are pivotally connected to a common pivot stud 19 which is arranged to slide within elongated slots 80 formed in the side plates of the lapping arm I8. To facilitate actuation of the toggle levers 15 and 16, a manually operable bell crank lever 8l is pivotally supported on a stud 82 carried by the lapping arm I8. The bell crank lever 8l is provided with a downwardly extending arm 83 which is connected by means of a pivot stud 84 with one end of a link 85. The other end of thelink 85 is pivotally connected with the stud 19.

A tension spring 86 is connected between the link 85 and a stud 81 carried by the lapping arm i8 and serves normally to hold the parts in an operative position as illustrated in Figsz' llaud 2. When it.r is. desired toly open; thef. lapping elements after aA lappingl operation has: been completed.,

the bell` crank lever 8l is. rocked. in; aacl'ockwise direction. (Figs.` l and: 2).. This. movement rocks thev armz83. also inv a clockwise: directiozrto move.

the link 85A towardathe lefti (Figs. 1'. and. 2.);` so that.

thex pivot. stud 1.8. slides within.. the*Y elongated slot 8.0' into. the extremeL left hand. end. thereof;

1 This: movement. of. the stud: 1.9: serves to: shiilt the tpggle leversl 1151 and. L6y from. a. locked position'. as illustrated in `E'igs. 1a. and 2: into` they pcsitiom illustrated in Fig.. 3: thereby swingingv the levers` 25. and; 2.6 about theirI supporting; pivots 2Jy and;l 2.8. so. as: to` movel the lapping elements :ily-32. and, 6l; to inoperative;v positionsr out.. of eng-age"-l ment.: with thez peripheral: surf/ace of the'f Worki piece 54.

Similarly when itis-,desired tozmovei thelapping elements:v to operativepositiozr, the bellLcranlt lever 8l; may. befmoved from thef position illus-Y tratedi in.y Eig.. 3in1 a. counter clockvv'seldirection to` shiftthe toggle-.levers 'l5 and;1.6!into:the-positionsillustrated; in.l 2', therebyswingingi the` levers- 25. ande 2li.` to. move the. lapping elements: 32h- 352'A and di'. intol operative;lappingv engagementI with the periphery.-y of thel work: piece 514:.. Duetofthe* voir;Qllsiszprovided with aeover plate-82 t'oif'aeilhk tate filling., the reservoir 9.0'. with't the desiredfiuid' orfsemi-fluid.lappinglcompound;

Thev operation: ofv this: improvedl` lapping arml will.y be4 readily apparent; from theiforegoingf dis-- closure. A work piece to be lapped is= positioned in the machine afterxwhich: theztoggle-lever' 8|-` is shifted.` to move the.lapping: elements 3ft-32S andi. 6l into; operative lapping engagement withthe peripheraksurfaceof the workpiecei'df; Due-tothefself-algning mountings;` the arcuate lapping surfaces l,E25-53 .anda '13; will:alignzthemselves the 1 surface toi bef-lapped. Byf adjustment?V ofi the f screw mechanisms above described, the lapping elements 3l--32 and 6I may be adjusted toward and from the work periphery to provide the desired lapping pressure between the lapping elements and the work surface being lapped. As previously explained the lapping elements 3l and 32 may be adjusted so as to compensate for taper on the work piece to lap a predetermined taper thereon or if desired may be adjusted to produce a predetermined tapered surface on the work. It will be readily apparent that by providing interchangeable lap holders 29, 3U and 60, various diameters of work may be lapped by merely interchanging the lap holders and lapping elements attached thereto.

It will thus be seen that there has been provided by this invention apparatus in which the .various vobjects hereinabove set forth together 7 -I'claim:

1. In a crankshaft lapping machine having a pivotally mounted lapping arm, a pair of pivotally mounted spaced lap-supporting levers on said arm, a toggle lever mechanism to move said levers to and from an operative position, an arcuate lapping element supported on one of said levers, a pair of spaced parallel adjusting screws on said lever to support said lapping element and to facilitate precise adjustment thereof, the axes of said screws lying in a plane passing through the work axis when the lapping element is in an operativel position to facilitate adjustment of said lapping element to compensate for taper on the work piece, an arcuate lapping element on the other lever, and means including a radially extending adjusting screw to facilitate precise adjustment of the latter element.

2. In a crankshaft lapping machine as claimed in claim 1, in combination with the parts and features therein specified, of a universal connection between said parallel adjusting screws and the first lapping element to facilitate self-alignment of said element relative to the surface of the work piece to be lapped, and a slidable connection between the second lapping element and its adjusting screw to facilitate a tangential selfalignment of said second element relative to the surface of the work to be lapped.

3. In a crankshaft lapping machine as claimed in claim 1, in combination with the parts and features therein specied, of a ball and socket connection between the parallel adjusting screws and the first lapping element to facilitate selfalignment of said element relative to the surface of the workpiece to be lapped about an axis substantially parallel to the work axis, and a tangentially arranged slideway interposed between the second lapping element and its adjusting screw to facilitate a tangential self-alignment of the second element relative to the surface of the work piece to be lapped.

4. In a crankshaft lapping machine having a pivotally mounted lapping arm, a pair of pivotally mounted spaced lap supporting levers on said arm, a toggle lever mechanism to move said levers to and from an operative position, a self-aligning arcuate lapping element supported on one of said levers, a pair of spaced parallel compound adjusting screws on said lever 'to support said lapping element and to facilitate a precise adjustment of said element, an arcuate lapping element on the other lever, and means including a compound adjusting screw interposed between said latter lever and the second lapping element to facilitate a precise adjustment of said latter element.

5. In a crankshaft lapping machine having a pivotally mounted arm, a pair of spaced pivotally mounted toggle-actuated levers on said arm, a self-aligning arcuate-shaped lapping element on one of said levers, means including a pair of spaced radially extending adjusting screws on said lever which are arranged normal to the axis of the work piece to be lapped to facilitate adjustment of said lapping element to compensate for taper on the Work piece, a radially adjustable member on the other lever, a dovetailed slideway on said member, an adjusting screw on said latter lever to facilitate a radial adjustment of said member, and an arcuate-shaped lapping element having a slideway mating with said dovetailed slideway, said dovetailed slideway being arranged to facilitate a self-aligning tangential adjustment of said latter element relative to the surface to be lapped.

6. In a crankshaft lapping machine having a movable crankpin lapping arm, a pair of spaced toggle-actuated levers pivotally mounted on said arm, a pair of spaced arcuate-shaped lapping elements on one of said levers, a pair of adjusting screws on said lever for precisely adjusting each of said elements, a ball and socket connection between each of said screws and the lapping element to provide a self-aligning movement of the element relative to the surface to be lapped, a tangentially arranged dovetailed slideway, an adjusting screw on the other arm to facilitate adjustment of said slideway in a substantially radial direction relative to the axis of the work piece being lapped, and an arcuate-shaped lapping element having a dovetailed slideway mating with said slide to facilitate a tangential self-aligning movement of the latter element relative to the surface of the work piece to be lapped.

HERBERT S. INDGE.

No references cited. 

